1. Field of the Invention
This invention relates generally to surgical apparatus and methods for repair of torn tissue, and more particularly to an apparatus and method for arthroscopic repair of a torn rotator cuff.
2. Brief Description of the Prior Art
The rotator cuff is composed of four tendons that blend together to help stabilize and move the shoulder. When a tear occurs in the rotator cuff of the shoulder, it is often necessary to re-attach the torn tendon or tendons to the bone of the humeral head.
In a common prior art rotator cuff reattachment technique, the torn cuff is punctured by a punch, and pre-threaded suture anchor screws (soft tissue fasteners) are drilled into the head of the humerus bone and the sutures threaded through the anchor screws are passed through the cuff in a difficult procedure using suture relay devices to-pass the sutures through the tissue. After the suture strands are passed through the tissue, they are knotted and tied together to secure the reattached rotator cuff to the humerus head. Other types of prior art suture anchors are conically shaped members that are pressed into holes drilled into the bone and engage the cancellous mass surrounding the drilled hole.
A major problem with the above described suture anchoring technique is that the threaded suture anchor screws or conically shaped anchors are threadedly or otherwise secured to the cancellous bone mass beneath the near cortex of the head of the humerus, and depend on this cancellous mass for fixation. It is well known that the cancellous bone mass is susceptible to osteopenic changes (diminished amount of bone tissue).
As a result, the pull-out strength of suture anchors which are depend on the cancellous bone mass beneath the cortex of the bone is subject to becoming diminished with time, and the anchors will tend to loosen, thereby possibly requiring a second operation to remove the loosened suture anchor.
Another problem with the conventional technique is that, in most cases, the sutures are not passed through the tissue when the anchor is set, and thus a difficult procedural step is required using devices such as punches and suture relays to pass and tie the sutures through the torn tissue.
The present invention is distinguished over the prior art in general, by an apparatus and method for arthroscopic repair of torn tissue such as a rotator cuff wherein torn tissue such as a rotator cuff is positioned on the bone exterior by a tissue grasper. A cannula is inserted through the skin substantially to the torn tissue. A drill guide is inserted into the cannula, a drill bit is inserted into the drill guide, and a hole is drilled through the torn tissue and completely through the bone. The drill bit is removed and an inner cannula is passed through the drill guide until its distal end is engaged on the torn tissue or alternatively passed through the hole until its distal end is at the far end of the drilled hole. A soft tissue anchor having expandable wings at its distal end and sutures secured to an eyelet at its proximal end is releasably connected to the distal end of a tubular deployment tool with the free ends of the sutures extending through the deployment tool. The deployment tool is passed through the inner cannula and drilled hole until the expandable wings clear the far end of the hole a sufficient distance to allow the wings to expand to a diameter larger than the diameter of the drilled hole. The deployment tool, inner cannula, drill guide, and cannula are removed and tension is applied to the suture to engage the expanded wings of the anchor on the exterior surface of the bone surrounding the drilled hole. A button is run down on the sutures through the cannula and secured on the torn tissue by the sutures such that the torn tissue is secured to the bone and the sutures are anchored to the hard exterior surface of the bone by the expanded anchor.
Unlike conventional soft tissues anchors which are anchored in the cancellous bone mass beneath the near cortex of the bone, the present invention provides a suture anchor which is engaged on the exterior of the far cortex of the bone and completely bypasses the cancellous bone mass. The cortex of the bone is much less susceptible to osteopenia than the cancellous interior of the bone.
With the present invention, the sutures are passed through the tissue when the anchor is set, and thus the difficult procedural step and use of devices such as punches and suture relays to pass and tie the sutures through the torn tissue is eliminated.
Calibrated markings on the deployment system of the present invention allow for precise measurement of the far cortex and precise measurement of the depth of insertion and engagement of the anchor device on the far cortex, such that structures beyond the cortex are not violated, and the button hold-down feature eliminates the traditionally difficult arthroscopic tying techniques.